The invention relates to a hybrid airship of a dirigible type, structural characteristic and a method of construction thereof. The invention is applicable in the aeronautical market, environmental enterprises, construction work, transport, hoisting and various other applications.
Currently the following categories of aerostats are known:
Rigid Aerostats.
In aircrafts of this type a truss frame structure is used, built with caves and stringers that define the format of the aircraft that is then coated with light materials such as impregnated fabric, rubber and materials that give the aircraft its final form. An aircraft of this type does not have any internal pressurization because the gas is stored in some balloons disposed internally within the structure and the entire mechanic load of the engines, cabins, rudders and other aircraft components is fixed to this structure.
Rigid aerostats are so far the safest and the fastest, and have bigger useful load capability than other aerostat types. Exemplary rigid aerostats were Graf the Zeppelin and the Hindenburg.
Semi-Rigid Aerostats.
These aircrafts use internal overpressure to maintain the shape of the aircraft, but utilize structural elements in key points to support the cabin, engines, rudders and other heavier items. They are usually covered with flexible and resistant materials (such as Hypalon®), like those used in rubber boats.
Non-Rigid Aerostats.
These aircrafts are covered with flexible material, pressurized generally with Helium, and its cabin is hanging. They are also known as Blimps (an example is the promotional Goodyear airship).
Metal-Clad.
These airships share some characteristics of rigid and non-rigid ones, using a very thin and hermetic metal balloon instead of a Hypalon or conventional rubber one. There are only two examples of this kind of airship, the aluminium balloon of Schwarz from 1897 and the ZMC-2.
Some lighter air airships, known as dirigible airships had limited resources and technology during the first decades of the past century (i.e. when they dominated the air). While the resources and technology are available today, development of dirigibles is still limited as it has been in the past, which in turn limits their production and utilization. Difficulties arise like security, dimensional stability in bad weather conditions (i.e. turbulences and hurricanes), resistance to thunderbolts, fire-resistance (ability not to take fire), controllability in adverse conditions, buoyancy in heavy rain conditions, instability when flying at higher velocities (more than 150 km/h), and other construction limitations with regard to the size of such aircrafts.
In addition to increased security considerations, production costs, and fear over another Hindenburg-like accident (the biggest dirigible that operated in the third decade of the last century), these limitations have deterred the development of such aircrafts. Engineering advancement in dirigible airships has evolved to focus on a semi-rigid structure. Utilizing hi-tech materials, such as carbon fiber and hardened aluminum as structural elements, and special high strength plastic and rubber sheets, such as Hypalon, provides better dimensional and operational stability.
Nonetheless modern semi-rigid dirigibles still have the same deficiencies as the old dirigibles, as follows: operational and structural instability in adverse conditions during bad weather, storms, and atmospheric gusts; sensitivity to rapid fluctuation of temperature and atmospheric pressure; difficulty to retain buoyancy in torrential rain conditions; complications and difficulties in securely executing proper techniques during landing and take-off; speed limitation of about 150 km/h; limitations in manufacturing technology to provide cost-viable model for larger size aircraft; high hydrogen and/or helium permeability coefficient that limits aircraft material from retaining gas efficiently; restrictions on hydrogen use due to high risk of combustion overshadowing its very desirable low-density property for aerostat flight and low production cost; radiation and electric discharge risk; difficulties in maintaining stable flying condition in fluctuating air density at various altitudes; weight of the ballast (used to adjust aircraft density to compensate for any fluctuation) greatly reduces fuel efficiency; economy of scale difficulties to support the construction of large hangers required in manufacturing large airships; large surface area and high drag coefficient generate poor aerodynamic airflow that greatly limits speed and fuel efficiency; and difficulty in maintaining stable airship position during landing and when stationary. The present invention proposed can reduce these limitations.